This invention relates to an intermediate gear type starter having an intermediate gear which is engaged with a pinion coupled to an electric motor and the ring gear of an internal combustion engine at the same time.
FIGS. 6 and 7 shows a conventional intermediate gear type starter disclosed, for instance, by Japanese Utility Model Unexamined Publication No. Sho. 58-84369. More specifically, FIG. 6 is a longitudinal sectional view showing essential components of the starter, and FIG. 7 is a sectional view showing the engagement of a shift ring.
In FIGS. 6 and 7, reference numeral 1 designates a DC motor. In the DC motor, an armature rotary shaft 3 is extended from its armature 2 in a forward direction (to the right in FIG. 6). A front bracket 5 coupled to the DC motor 1 supports the front end portion of the rotary shaft 3 through a sleeve bearing 6.
An over-running clutch 7 is slidably mounted on the rotary shaft 3. The over-running clutch 7 is designed as follows: That is, the over-running clutch 7 comprises; a clutch outer member 8 which is engaged with a helical spline gear formed on the rotary shaft 3 so that the rotation of the rotary shaft 3 is transmitted to the clutch outer; and a clutch inner member 9 for transmitting the rotation through rollers 10 to the clutch outer member 8 in one way. The clutch inner member 9 is mounted through a sleeve bearing 17 on the rotary shaft 13. The front end portion of the clutch inner member 9 is formed into a pinion 11. A clutch cover 12 is secured through a stiffening plate 13 to the clutch outer member 8 by staking. A locking ring 14 is fixedly mounted on the clutch outer member 8, thus forming an engaging groove 15 with the step of the clutch outer member 8. An eccentricity regulating ring 16 is secured to the inner cylindrical surface of the clutch outer member 8.
Further in FIG. 6, reference numeral 20 designates a fork-shaped shift lever the two prongs of which are engaged with the aforementioned engaging groove 15. It is supported, at its middle portion, namely, its fulcrum portion, by a receiving plate 21. The receiving plate 21 is supported through a shock absorbing spring 23 on a grommet 22 mounted on the housing of the motor 1. The other end portion of the shift lever 20 is coupled to the end portion of the plunger of an electromagnetic switch (not shown) mounted on the motor, so that the shift lever 20 is swung about its fulcrum portion.
Further in FIG. 6, reference numeral 24 designates an intermediate shaft which is secured to the front bracket 5 in such a manner as to be in parallel with the rotary shaft 3; 25, a grommet; 26, an intermediate gear supported by the intermediate shaft 24 through a sleeve bearing 28 which is secured to the inner wall of the intermediate gear. The intermediate gear 26 has a boss 26a, in the outer surface of which an annular groove 27 is formed. A shift ring 29 is secured to the outer cylindrical wall of the clutch cover 12. The shift ring 29 has an annular flange 29a protruded radially, which is engaged with the annular groove 27 in the boss 26a of the intermediate gear 26 as shown in FIG. 7.
Now, the operation of the starter thus constructed will be described.
Upon energization of the exciting coil of the electromagnetic switch (not shown), the plunger is attracted, lo so that the shift lever 20 is turned counterclockwise to move the over-running clutch 7 in the forward direction (or in the direction of the arrow A) until the over-running clutch 7 strikes against the stopper 18 mounted on the rotary shaft 3. As the over-running clutch 7 is moved in this manner, the intermediate gear 26 is moved along the intermediate shaft 26 through the shift ring 29 until it is engaged with the ring gear 30 of the internal combustion engine. Thereafter, the stationary contact means of the electromagnetic switch is closed, so that current is applied to the circuit of the DC motor 1 to rotate the armature 2. The rotation of the rotary shaft 3 is transmitted through the over-running clutch 7, the pinion 11 and the intermediate gear 26 to the ring gear 30 of the internal combustion engine to start the latter.
As was described above, in the conventional intermediate gear type starter, the intermediate gear is moved in association with the over-running clutch 7. For this purpose, the shift ring 29 is fixedly secured to the over-running clutch 7. The force of movement of the over-running clutch 7 is applied to the intermediate gear through the annular flange 29a of the shift ring 29 engaged with the upper portion of the annular groove 27 of the intermediate gear 26; that is, the moment of the force acts on the intermediate gear 26, thus obstructing the smooth axial movement of the intermediate gear.
In addition, the conventional intermediate gear type starter is disadvantageous in the following point: In providing lo a cover for the starter for dust-proof, corrosion-proof and water-proof, components of a cover, mounting bolts or the like are required, thus increasing the number of components.